Lyme Regis, presented to the Oxford Museum by Viscount Cole, enclosing within its ribs scales, and digested bones of Fishes, in the state of Coprolite. This coprolitic mass seems nearly to retain the form of the stomach of the animal. c, Coracoid bone. d, Scapula. e, Humerus. f, Radius. g, Ulna. (Scharf. Original.)

PLATE 14. V. I. p. 152.

Skeleton of the Trunk of a small Ichthyosaurus in the

Fig. 5. Nearly flat articular surface of (probably) the third cervical vertebra of the same large Individual as Fig. 3. This surface of the bone has only a small cylindrical depression at its centre, instead of the deep, conical cup of the more flexible vertebræ, C. B. E.

Near its upper margin is a wedge-shaped elevation (b) and near the inferior margin, a notch or furrow (a.) These salient and re-entering portions articulated with corresponding depressions and projections on the surface of the adjacent vertebra, and acted as pivots, admitting a limited amount of lateral vibrations, and at the same time preventing any slip, or dislocation.

Fig. 6. Concave surface of Fig. 5.; the wedge-shaped projection near its lower margin (a) must have articulated with a corresponding groove or depression on the front of the vertebra adjacent to it, like that at (Fig. 5. a.) As one surface only of these vertebræ had a conical cavity, the intervertebral substance must have formed a single cone, admitting in the neck but half the amount of motion, that the double cones of intervertebral matter allowed to the dorsal and caudal vertebræ, (C. B. E.) where greater flexure was required, to effect progressive motion by vibrations of the body and tail.

These dispositions of the articulating facets of the cervical vertebræ, acting in conjunction with the three sub-vertebral wedges before described, afford an example of peculiar provisions in the neck of these gigantic Reptiles, to combine a diminished amount of flexure in this part, with an increased support to their enormous heads.

It is probable that every species of Ichthyosaurus had peculiar variations in the details of the cervical vertebræ, and subvertebral wedges, and that in each species these variations were modified by age.

In the Gavial Mr. Mantell has recently observed that the first caudal vertebra is doubly convex, like the last cervical vertebra in Turtles. These peculiar contrivances give to the animals in which they occur increased flexibility of the Tail and Neck.

Oxford Museum, from the Lias at Lyme Regis, containing within the ribs, a coprolitic mass of digested bones, interspersed with scales of fishes. a, Furcula. b, Clavicle, c, Coracoid bone. d, Scapula. e, Humerus. (Fisher. Original.)

PLATE 15. V. I. p. 147.)

The specimens are all of the natural size except where the figures denote otherwise. (Original.)

1 and 2. Intestines of the two most common English species of Dog-Fishes, injected with Roman cement.

The vascular structure, which is still apparent in the desiccated membrane, resembles the impressions on the surface of many Coprolites.

3. Coprolite from the Lias at Lyme, exhibiting the spiral folding of the plate of digested bone, and impressions

of the intestinal vessels and folds upon its surface. (See Note, V. I. p. 152. et seq.)

3'. Magnified scale of Pholidophorus limbatus, embedded in the surface of the Coprolite, Fig. 3. This scale is one of those that compose the lateral line, by which a tube passes to convey mucus, from the head, along the body of fishes; a. is the hook, on the superior margin, which is received by a depression on the inferior margin of the scale above it, corresponding with b.; c. is the serrated edge of the posterior margin, perforated at e. for the passage of the mucous duct; d. is a tube on the interior surface of the scale to carry and protect the mucous duct. (See note V. I. p. 150.)

3". Exterior of the scale 3'.; the same parts are repre

sented by the same letters; the larger portion is covered with enamel; the smaller portion next d. is the bony root forming the anterior margin of the scale.

4. Transverse section of another Coprolite from Lyme, showing the internal foldings of the plate, with sections of scales of fishes embedded in it.

5. Exterior of a spiral Coprolite, from the Chalk Marl, near Lewes, showing folds and vascular impressions analogous to those in No. 3.

6. Longitudinal section of another Coprolite, from the same Chalk Marl, showing the spiral manner in which the plate was folded round itself.

7. Exterior of another spiral Coprolite, from the Chalk at Lewes, showing vascular impressions on its surface, and the transverse fracture of the spiral fold at b.

In many other figures of Plate 15, a similar abrupt termination of the coiled plate is visible at b. 8, 9. Two other small species of spiral Coprolites in chalk; these as well as Figs. 5, 6, 7, are probably derived from fishes found with them in the chalk, near Lewes. 10, 11, 12. Coprolites from the Lias at Lyme, exhibiting well-defined characters of the spiral fold, with vascular impressions on their surface.

13. Similar appearances on a Coprolite found by Dr. Morton in the Greensand of Virginia.

14. Coprolite from the Lias at Lyme, bearing strong corrugations, the result of muscular pressure received from the intestines.

15. Transverse section, showing the abrupt termination of the folded plate in Fig. 14, and representing the flattened form of the spiral intestine.

16. Longitudinal section of the intestinal tube of a recent Shark, showing the spiral valve that winds round its interior, in the form of an Archimedes screw; a similar spiral disposition of the interior is found in intestines of Dog-Fishes, Figs. 1 and 2.

17. Coprolite from Lyme, containing large scales of Dapedium politum.

18. Coprolite from the Lias at Lyme, containing undigested bones of a small Ichthyosaurus.

PLATE 15'. V. I. p. 156.

Cololite, or petrified intestines of a fossil fish from Solenhofen. (Goldfuss.)

PLATE 16. V. I. p. 157.

1. Conjectural Restoration of the Skeleton of Plesiosaurus dolichodeirus. (Conybeare.)

2. Skeleton of Plesiosaurus dolichodeirus, in the British Museum, from the Lias at Lyme Regis. (Scharf. Original.)

PLATE 17. V. I. p. 158.

A nearly entire and unique skeleton of Plesiosaurus dolichodeirus, 5 feet 7 inches long, from the Lias of Street, near Glastonbury. This skeleton forms part of the splendid series of fossil Saurians, purchased for the British Museum, from T. Hawkins, Esq. in 1834. See V. I. p. 162, and Note. (Hawkins.)

PLATE 18. V. I. p. 160, Note.

1. Under jaw of Plesiosaurus dolichodeirus, forming part of the series last mentioned. (Original.)

2. Head of the Plesiosaurus, figured in Pl. 16. Fig. 2. seen from beneath. (Original.)

3. Ventral portion of the ribs of the Plesiosaurus, figured in Pl. 17. See V. I. p. 162. (Original.)

a. c. Central bones forming the crown of the sterno-costal arch. b. triple series of intermediate bones between the central bones, a. c. and the true ribs, d. d. e. e. lower extremity of coracoid bones.

PLATE 19. V. I. p. 160.

Fig. 1. A beautiful specimen of Plesiosaurus macrocephalus hitherto undescribed, found in the Lias marl at Lyme Regis, by Miss Anning, and now in the collection of Lord Cole. (Original.)

On comparing this figure with those of P. Dolichodeirus at Pl. 16, 17. The following differences are obvious:

1. The head is very much larger and longer, being nearly one-half the length of the neck.

2. The vertebræ of the neck are thicker and stronger in proportion to the greater weight they had to sustain.

3. The hatchet-shaped bones differ in form and size, as may be seen by comparing them with those of P. dolichodeirus. Pl. 19. Fig. 2. and Pl. 17.

4. The bones of the arm and thigh are shorter and stronger than in P. Dolichodeirus, and corresponding differences may be traced throughout the smaller bones of the Paddles; the general adjustment of all the proportions being calculated to produce greater strength in the P. Macrocephalus, than in the more slender limbs of P. Dolichodeirus.

These differences are not the effect of age; as the two specimens, from which they are here described, are nearly of the same length.

Fig. 2. Hatchet-shaped bones of the neck of Plesiosaurus Dolichodeirus, copied from the specimen figured in

Pl. 17.

3. Anterior extremity of an insulated lower Jaw of Plesiosaurus, from the Lias at Lyme Regis, in the British Museum, part of the collection of Mr. Hawkins. V. I. p. 160. Notc. (Original.)

4. The entire bone, of which Fig. 3. forms part, reduced to a small scale.